Field of the Invention
The present invention relates to a capacitive distance sensor.
Description of the Related Art
As a sensor for measuring the distance (e.g. gap) between objects or the like, a capacitive distance sensor is known. As such a distance sensor, Japanese Patent Laid-Open No. 2013-516601 discloses a sensor that attempts to improve the performance of the sensor by providing guard electrodes around or behind a sensor electrode (sensing electrode).
When a measurement target is a movable object or has a curved measurement surface, it is necessary to narrow the measurement range and measure the distance in a spot to improve measurement accuracy. To narrow the measurement range, the area of the sensor electrode needs to be reduced.
However, a lead portion to input a signal from a measurement signal source is connected to the sensor electrode. When the sensor electrode is made small, the capacitance between the lead portion and the measurement surface may degrade the measurement accuracy.